Meconium Aspiration Syndrome

Aka: Meconium Aspiration Syndrome, Meconium Aspiration, Meconium Aspiration Pneumonia, Meconium Pneumonitis

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II. Epidemiology

  1. Prevalence
    1. Meconium-stained amniotic fluid is present in up to 15% of deliveries
    2. Meconium Aspiration Syndrome occurs in only 1% of all deliveries
  2. Gestational Age
    1. Meconium is only formed by the fetal Gastrointestinal Tract after 34 weeks

III. Pathophysiology

  1. Meconium Aspiration most often occurs in utero prior to delivery
  2. Meconium contains gastrointestinal fluids which cause localized inflammation
  3. Meconium Aspiration results
    1. Severe airway inflammation
    2. Airway obstruction
    3. Inactivation of surfactant (and decreased surfactant production)
    4. Pneumonia risk

IV. Risk Factors

  1. Advanced Gestational Age
  2. Thick meconium
  3. Emergency cesarean delivery
  4. APGAR <7
  5. Nonreassuring Fetal Heart Rate

V. Signs

  1. Hypoxia and Cyanosis
  2. Respiratory distress
    1. Tachypnea
    2. Grunting
    3. Retractions
  3. Lung Exam
    1. Pulmonary rales and rhonchi
    2. Chest may appear barrel-shaped (due to air trapping)
  4. Skin
    1. Meconium stained skin

VI. Differential Diagnosis

  1. See Newborn Respiratory Distress
  2. See Neonatal Distress Causes

VII. Diagnosis: Criteria

  1. Meconium-stained amniotic fluid
  2. Respiratory Distress in the Newborn AND
  3. Supplemental Oxygen required in the first 2 hours of life to maintain O2Sat >92% AND
  4. Persists >12 hours AND
  5. No other alternative cardiopulmonary disorders identified

VIII. Imaging: Chest XRay

  1. Patchy infiltrates (fluffy densities) and Atelectasis
  2. Hyperinflation
  3. Lung Consolidation changes

IX. Management: Meconium stained infant

  1. See Respiratory Distress in the Newborn
  2. See Newborn Resuscitation
  3. Initial infant Resuscitation is the same for infants without meconium staining
  4. Oxygenation and ventilation
    1. Supplemental Oxygen 21-50% FIO2 to keep Oxygen Saturation >90%
    2. Non-Invasive Positive Pressure Ventilation (e.g. N-CPAP)
    3. Endotracheal Intubation may be required
    4. ECMO may be used in severe cases
  5. Surfactant
    1. May improve oxygenation
    2. May decrease the risk of persistent Pulmonary Hypertension and other complications

X. Prevention

  1. Suctioning head at the perineum and endotracheal suctioning are no longer recommended
    1. See pathophysiology above regarding in utero aspiration
    2. Risk of airway injury complications outweigh any potential benefit
    3. Vain (2004) Lancet 364:597-602 [PubMed]
  2. Amnioinfusion does not decrease Meconium Aspiration risk
    1. Fraser (2005) N Engl J Med 353:909-17 [PubMed]

XI. Complications

  1. Persistent Pulmonary Hypertension
  2. Pneumonia risk
  3. Bronchial hyperactivity
  4. Asthma
  5. Developmental Delay

XII. References

  1. Buel (2026) Am Fam Physician 113(1): 35-41 [PubMed]
  2. Hermansen (2015) Am Fam Physician 92(11): 994-1002 [PubMed]

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